Orateur
Siyang Li
(University of California, Berkeley)
Description
The tension between early- and late-universe determinations of the Hubble constant has placed extraordinary demands on the precision and accuracy of the extragalactic distance ladder. I review the current status of two standard candles - the Tip of the Red Giant Branch (TRGB) and the J-region Asymptotic Giant Branch (JAGB) - as independent calibrators of Type Ia supernovae. For each method, I discuss theoretical foundations, systematic error budgets, and recent observational progress enabled by HST and JWST. I then compare TRGB- and JAGB-based H0 determinations to one another and to Cepheid-based results, and conclude with a discussion of outstanding systematics and priorities for the field.